Rust preventive chromium compounds and compositions containing them



Patente i1 uNi an STATES PATENT race nusr PREVENE CHROMIUM coM- roorms.anc comrosrrrons con- "IAINING THEM No Drawing. Application July 16,1946, Serial No. 683,991

15 Claims.

This invention relates to the prevention of corrosion of metals, and inparticular concerns new compositions of matter adapted to inhibitorprevent the corrosion or rusting of metal surfaces when applied theretoin the form of a coating.

In the shipping and storage of metal articles, particularly ferrousmetal articles having me.- chined surfaces, it is highly desirable toprotect such articles from the corrosion or rusting which normallyoccurs when metal surfaces are exposed to the atmosphere for any lengthof time. While such protection should remain eife'ctive over longperiods of time under very adverse conditions of humidity. it shouldlikewise be of such nature that.

it can readily be removed when it is desired to place the metal articleinto use. Among the various means employed for providing such protectionagainst corrosion, that of applying a, film or coating of anon-corrosive liquid coating composition to the metal surface hasenjoyed widest use by reason of its economy and ada tab lity to allsorts of metal articles ranging from sim le pieces to complicatedmachine assemblies. Such liquid corrosion preventive compositions oftencomprise a mineral, or other non-drying oil base having a corrosionpreventive material dispersed or dissolved therein. and are henceusually referred to generically as slushing olls even though in someinstances they may not actually contain anoil.

The slushing oils heretofore employed, however, have been subject tonumerous disadvamta es. In some instances they have be n too expensivefor widespread general use. whereas in others they are too difllcult toremove from surfaces to which they have been applied. Many of them .havenot proved efiective over sufficiently long periods of time, or have notprovided the desired protection against corrosion under extreme climaticconditions such as those encountered in the tropics or at sea.

Accordingly, it is an object of this invention to provide new corrosionpreventives capable of use in inhibiting or preventing the corrosion orrusting of metal surfaces overlong periods of time and under adverseclimatic conditions.

Another object is to provide corrosion preventives which can readily bedissolved or dispersed in a suitable liquid vehicle to form inexpensiveand highly efiective slushing oil compositions.

A further object is to provide improved slushing oil compositions.

A still further object is to provide highly efficient slushing oilcompositions adapted for ready 5 application and removal from all typesof metal articles.

Other objects will be apparent from the following detailed descriptionof the invention, and various advantages not specifically referred toherein will occur to those skilled in the art upon employment of theinvention in practice.

I have found that the above objects and attendant advantages may berealized in certain new corrosion preventives obtained'as products ofreaction between chromium trioxide and certain substituted oxazolinecompounds. More particularly, I have found that products havingexcellent inhibiting action on the corrosion of metals may be obtained.by reacting chromium trioxide with an oxazoline compoundhaving thegeneral wherein R represents the hydrocarbon residue of a fatty ornaphthenic acid or of an acidderived from the oxidation of petroleumproducts; Y and naphthenic acid or of an acid derived from the oxidationof petroleum products as herein employed refers to the non-carboxylic,or hydrocarbon,portion of fatty, naphthenic, or oxidized petroleum acidsof the formula R-COOH. Examples of such oxazoline compounds include 2-oleyl-2-oxazoline, 2-oleyl-4-methyl 4 hydroxymethyl-Z-oxazoline,2-heptadecyl 4,4-cliethyl-2- oxazoline', 2 -undecyl 4-propyl-4-ethyl-5methylz-oxazoline, 2-pentadecyl-4-butyl-2 -oxazo1ine, 2

heptadecadienyl-4-i sopropyl-4-hydroxymethyl-2- oxazoline,2-dodecyl-4-hydroxybutyl-2-oxazoline, 2oleyl-4.4,5-trimethyl-2-oxazoline, and analogous oxazoline compounds inwhich the substituo ent in the 2-position is the hydrocarbon residue ofa naphthenic acid or an acid derived from the oxidation of petroleumproducts. The latter acids are high molecular weight saturated aliphaticcarboxylic and hydroxycarboxylic acids obtained in admixture withhydrocarbons, aliphatic alcohols and ketones, and keto-alcohols bypartially oxidizing petroleum hydrocarbons in the liquid phase atelevated temperatures and pressures as disclosed, for exam le, in U. S.Patents Nos. 1,690,768 and 1,690,769.

Such substituted oxazolines may be prepared in a number of ways, one ofthe most convenient of which consists in reacting a fatty r naphthenicacid, or an acid derived from the oxidation of petroleum products, witha beta-amino-alcohol with the elimination of two molecules of water.This reaction may be described by the equation:

wherein R, Y, Y, and Y" have the meanings hereinbefore defined. Thisreaction takes place readily, and can be effected simply by heating anequimolecular mixture of the two reactants to a temperature at whichwater distills from the mixture. If desired, an inert solvent, such asbenzene or toluene, may be employed to facilitate the vaporization andremoval of water from the reaction as an azeotropic mixture. Uponcompletion of the reaction, as evidenced by two mols of water havingbeen distilled off, the reaction mixture may be washed and/or distilledunder vacuum to recover and purify the oxazoline product. 4

Any fatty acid, particularly a higher fatty acid containing from 10 to'20 carbon atoms, such as oleic acid, linoieic acid, stearic acid,palmitic' acid, lauric acid, arachidic acid, or mixtures thereof such asare obtained from natural products, a naphthenic acid, or an acidderived from the oxidation of petroleum, may be employed as the acidreactant, and any compound of the formula wherein Y, Y and Y" have themeanings hereinbefore defined, may be employed as the betaamino-alcoholreactant. Thus, oleic acid may be reacted with2-amino-Z-ethyl-propanediol- 1,3 to form2-oleyl-4-ethyl-4-hydroxymethyl-2- oxazollne, myristic acid may bereacted with 2- amino-ethanoi to form 2-tridecyl-2-oxazoline, llnoleicacid may be reacted with 2-amino-2- propyl-butanediol-L4 to formZ-heptadecadienyl- -propyl-4-hydroxyethyl-2-oxazoline, lauric acid maybe reacted with 1-amino-1-ethyl-1-propylisopropanol to form2-undecyl-4-ethyl--propyl- 5-methyi-2-oxazoline, etc.

The oxazoline compounds of the present class may likewise be prepared byreduction and dehydration of the appropriate nitro-alkylol esters by aprocess similar to that disclosed in U. S. Patent 2,372,409.

The reaction between chromium trioxide and theherein defined substitutedoxazolines to form the products which are employed as corrosionpreventives in accordance with the invention is carried out by heatingthe oxazoline compound with between about 5 and about '25, preferablybetween about 8 and about 12, per cent by weight thereof of chromiumtrioxide. The latter is conveniently employed in the form of a 10-20 percent aqueous solution, although it may be used in crystalline form. Thereaction takes place readily at temperatures between about 100 C. andabout 250 C. and its completion is usually indicated by the reactionmixture assuming the dark green color which is characteristic of certainchromic compounds. Upon completion of the reaction, the mixture iswashed with hot water to remove any unreacted chromium trioxide, wherebythe reaction product is obtained as a high-boiling dark green viscousliquid which is substantially insoluble in water but is readily solublein a variety of organic solvents, e. g., hexane, benzene,

carbon tetrachloride, petroleum ether, etc.

The exact identity of the chromium-containing reaction products thusobtained and the nature of the reaction by which they are formed are notaccurately known, and accordingly the reaction products are hereindisclosed and claimed as such, rather than as chemical compounds whoseidentity can only be speculative.

While the above-described reaction products may be employed per se ininhibiting or preventing the corrosion or rusting of metals, by reasonof their high viscosity they are more readily "applied to metal surfacesin the form of a solution or dispersion in a liquid vehicle. Forexample, they may be dissolved in a relatively light organic solvent,such as" hexane, benzene, petroleum ether,

carbon tetrachloride, or a light naphtha, to form slushing oilcompositions of a viscosity suitable for application to metal surfacesby dipping, spraying, or brushing "procedures; Such light solvent willevaporate leaving a thin protective coating of the corrosion inhibitingreaction product on the metal surface. When it is desired to use themetal article thus protected, the'corrosion preventive coating mayreadily be removed by' washing with a suitable solvent. Gasoline is anexcellent solvent for this purpose since it is cheap and universallyavailable. The light petroleum distillate known as Stoddard solvent hasbeen found particularly suitable for use as the solvent in preparingliquid protective coating compositions comprising the new corrosionpreventives, and may also be used in the subsequent removal of thprotective coating.

The amount of solvent employed will depend upon the nature of thesolvent itself as well as upon the thickness of the coating desired onthe metal. Ordinarily, however, suitable composie tions will contain upto about 75 per cent, preferably between about- 25 and about '75 percent, by weight of the solvent. When it is desired to apply a thickcorrosion preventive coating, the

amount of solvent is kept near the minimum, whereas if a thin coating ispreferred, the amount of solvent may be considerably increased. For mostapplications, a composition comprising equal parts of solvent and thecorrosion preventive material will be found very satisfactory.

While the corrosion preventive reaction products of the presentinvention eflectively inhibit the corrosion or rusting of metals forextended periods of time, I have found that the period of protection maybe further extended through the use of a water-insoluble soap inconjunction with such products. Thus, for example, the period ofprotection against corrosion provided by the reaction product ofchromium trioxide and 2-oleyl- 4-methy1-4-hydroxymethyl-2-oxazoline isconcomplete.

be substituted other metals which form waterinsoluble soaps, e. g.,calcium, barium, strontium. aluminum, etc. Similarly, the soya bean. ollfatty acid may be substituted by the fatty acids of other oils, such ascotton-seed, peanut, tung, linseed, perilla, corn, and oiticica oils. Inplace of natural oil fatty acids which are composed of mixtures ofindividual acids, a single fatty acid, such as palmitic, oleic, stearlc,or linoleic acid may be used. The amount of such soaps may vary fromabout 25 to about '75 per cent of the combined weight of soap andcorrosion preventive reaction product.

In testing and demonstrating the efiiciency of the new reaction productsas corrosion preventives, a modification of the testing proceduredescribed in paragraph F-3a(7) of the "Bureau of Ships Ad InterimSpecifications, 52C18 (INT), dated March 1, 1944, is convenientlyemployed. According to this test, two polished panels of SAE 1020 steel,6 inches long by 3 inches wide and ,4; inch thick, are immersed in asolution consisting of equal parts of the corrosion preventive beingtested and a petroleum distillate solvent having the followingcharacteristics:

Gravity, API 48.5 Flash point (TCC), F 104 Initial boiling point, "F 312'End boiling point, "F 394 Thesteel panels are removed from thissolution and allowed to dry for 48 hours, during which time the solventevaporates leaving a residual coating of the corrosion preventivematerial on the panels. The panels 50 prepared, together with anydesired blank panels, are then subjected to an accelerated corrosiontest in a National Carbon Weathering unit, model X-l-A. In thisapparatus, the specimens to be tested are hung on a circular racl-rwhich rotates once every two hours. During this period the panels aresprayed for minutes with fresh water, and for the remaining hour andminutes they are subjected to intense ultraviolet radiation produced bya carbon arc lamp. The panels are examined daily for the appearance ofrust, the time required for the appearance of the first rust spot beingtaken as a measure of the efficiency of the corrosion preventive undertest.

The following examples will illustrate several ways in which theprinciple of the invention has been applied, but are not to be construedas limiting the same.

Example, I

Approximately 100 parts b weight of 2-oleyl- 4-methyl 4 hydroxymethyl 2oxazoline was mixed with approximately 10 parts by weight of chromiumtrioxide at room temperature. The 2- oleyl 4 methyl-4-hydroxymethyl2-oxazoline employed wasa commercial product boiling in the range of174-305 C. and havin an average molecular weight of 350, and thechromium trioxide was employed in the form of a 20 per cent aqueoussolution. The mixture was slowly heated with stirring to a temperatureof about 95-115 C., and was held at this temperature until foamingsubsided and dehydration was practically The temperature was then raisedto 215-230 C. over a period of 30-60 minutes. and was held in this rangefor about 30 minutes. During this final heating period the reaction wascompleted and the mixture became'considerably more viscous. It was thencooled and washed with boiling water to remove any water-solublematerials, and the water-insoluble product was heated to drive off anyresidual water. The reaction product thus obtained was a dark greenliquid having the consistency of thick honey. It was highly soluble in avariety of organic solvents, and had an average molecular weight of1160. Its composition by chemical analysis was as follows:

Per cent by weight Carbon 66.0 Hydrogen 10.4 Nitrogen 3.2 Chromium 56Oxygen (by difference) 14.8

This reaction product was tested for effectiveness as a corrosionpreventive by the accelerated weathering test previously described. Ofthe two panels coated with the reaction product, one showed rusting onlyafter 31 days of continuous treatment in the weatherometer, while theother panel did not corrode until it had been in the weatherometer for59 days. In contrast, both an uncoated panel and a panel coated with2-oleyl- 4-methyl-4-hydroxymethyl-2-oxazoline considerable rusting inone day. For purposes of checking, two more sets, each consisting of twopanels coated with the reaction product, were tested. One of the panelscorroded on the thirtyfirst day, but the remaining three did not corrodeuntil after 51 days in the weatherometer,

Example II was a so tested. The panels which had been treated with thecomposition containing the reaction product andthe zinc'soap of soyabean oil were still bright and shiny and had no rust spots after sixtydays of continuous treatment in the weatherom'eter, whereas the panelcoated only with the zinc soap of soya bean oil corroded after nine daysof treatment.

Example III 2-heptadecyl-4-methyl 4. hydroxymethyl-2- oxazoline wasprepared by dissolving equimolecular quantities of stearic acid and2-amino-2- methyl-propanediol-1.3 in toluene, and heatinr! to atemperature at which water was distilled ofi in the form of an azeotropewith the toluene. Upon completion of the reaction, as evidenced by theremoval of two molecular equivalents of water in this manner, thereaction mixture was transferred to a distillation flask and wasdistilled under vacuum, whereby the oxazoline product was obtained as awaxy white solid having a, melting point of about 50-58 C. It had thefollowing analysis:

' Per cent by weight Carbon 74.2 Hydrogen 11.8 Nitrogen 4.1 Oxygen (bydiiference) 9.9

A sample of this product was heated to a temperature of about C., and 10per cent by weight of chromium trioxide was added in the form of a 20per cent aqueou solution. The mixture was then showed slowly heated withstirring to a temperature of about l-.-l25 C., and was maintained atthis temperature until dehydration was practically complete. Thetemperatur was then raised to, about 205-220 C. for about 15 minutes,after which the reaction mixture was cooled and was washed with boilingwater to remove any excess chromium trioxide. The water-insolublereaction product was dried by heating, and was obtained as a veryviscous dark green liquid. A sampe of this product was dissolved in anequal weight of light petroleum distillate to form a slushing oilcomposition which was then applied to polished SAE 1020 sfeel'testpanels. When these panels were subjected to the corrosion test ashereinbefore described, they showed signs oi corrosion only after 68days exposure in the weatherometer.

' Example IV 2oleyl-2-oxazoline was prepared from oleic acid andbeta-amino-ethanoi as described in Example III. The product was obtainedas a viscous liquid distilling at 180-220 C. under 1.5 mm. pressure,from which there was isolated by cooling a white crystalline solidhaving a melting point of about 65-70 C. A sample of the liquid productwas heated with per cent by weight of chromium trioxide as described inExample III to obtain a dark green viscous liquid reaction product.Steel panels which had been coated with this product in the form of a 50per cent solution in Stoddard solvent, and then corrosion tested asherein described, showed evidence of corrosion after 19 days exposure inthe weatherometer.

Example V trioxide, as described in Example III, and the resultingreaction product was dissolved in an equal weight of Stoddard solvent.Steel panels which had been coated with this solution by dipping showedsigns of rusting only after days exposure in the weatherometer. ExampleVI Approximately 275 parts by weight of a naphthenic acid having a.neutralization equivalent of 275 were reacted with 119 parts by weightor 2-amlno-2-ethyl-propanediol-1,3, as described in Example III, toobtain a 4-ethy1-4-hydroxymethyl-z-oxazoline compound having an'aphthenic acid residue substituted in the 2-position. This product wasa dark viscous liquid which distilled in the range 2Q0250 C. under 1.2mm. ressure. 6

Upon reacting this produchwi-th chromium trioxide, as described inExample III, there was obta'ncd a viscous dark green l'quid which, whentested as a corrosion preventive as herein described. gave an average or25 days protection against rustin in the weatherometer. An analogousproduct, prepared by reacting chromium 'trioxide with the oxazolinecompound obtained from the same naphthen'c acid and 2-amino-2-methyl-propanediol-l,3, gave an average of 35 days protection in theweatherometer.

Example VII A mixture of approximately 220 parts by weight of petroleum,and 105 parts by weight 01' 2-amino- 2-methyl-propanediol-1,3 was heateduntil two molecular equivalents of water had been distilled ofl toobtain a 4-methyl-4-hydroxymethyl-2- oxazoline compound having theoxidized petroleum acid residue substituted in the2-position. Thisproduct was a thick dark liquid distilling in the range 100-l90 C. under1.2 mm. pressure. Upon reacting this product with 10 per cent by we'ghtof chromium trioxide there was obtained a dark green viscous liquidwhichgave an average of 27 days protection against rusting when testedas a corrosion preventive in the weath erometer. An analogous product,prepared by reacting chromium trioxide with the oxazoline compoundobtained from the same mixture of ac ds derived from the oxidation ofpetroleum and 2-amino-2-ethyl-propanediol-1,3, gave an average of 29days protection against corrosion in the weatherometer.

Example VIII Example IX 2 pentadecyl 4 ethyl 4 hydroxymethyl-2-oxazoline was obtained as a viscous liquid distilling at 192-215 C.under 1.2 mm. pressure by distilling two molecular equivalents of waterfrom an equimolecular mixture of palmitic acid and2-amino-2-ethyl-propanediol-1,3. Upon chilling, a white solid having amelting point 01' 36-38 C. crystallized from the liquid product. Asample of the liquid material was heated with 10 per cent by weight ofchromium trioxide in aqueous solution to obtain a dark green liquidreaction product which was eifectiveas a corrosion preventive for aperiod of 18 days when tested as described above.

For purposes of providing comparative test data. the slushing oilcompositions prepared in the above examples all comprised a reactionproduct of the present class dissolved in a standard light petroleumdistillate solvent. However, a variety or other solvents or liquiddispersing media may be employed to prepare a wide variety of tions.Thus, the reaction products herein described may be dissolved ordispersed in heavier oils and the like or even petrolatum to provide 0thick liquid or grease-like compositions. Similarly, various additives,particularly the watersoluble soaps herein disclosed, may beincorporated in such compositions for the further modification of theirproperties.

Other modes of applying the principle or my invention may be employedinstead of those explained. change being made as regards the ingredientsor methods employed, provided the features set forth in any of theappend-ed claims be attained.

This application is a continuation-in-part oi" my co-pendingapplication, Serial Number 633,557, flied December 7, 1945.

I claim:

of a mixture of acids derived from the oxidation l. Achromium-containing product obtained by quantities of oleic acid and 2--N YII e Y! wherein R represents the hydrocarbon residue of an acidselected from the group consisting of higher fatty acids, naphthenicacids, and acids derived from the liquid phase partial oxidation ofpetroleum products, Y and Y each represents a substituent selected fromthe group consisting of hydrogen and lower alkyl groups. and Y"represents a substituent selected from the class consisting of hydrogen,lower alkyl groups, and lower hydroxyallgyl groups, with chromiumtrioxide at a temperature between about 100 C. and about 250 C.

2. A chromium-containing product obtained by heating an oxazolinecompound having the general formula RC CHY N Y" i wherein R representsthe hydrocarbon residue of a naphthenic acid, Y and Y' each represents asubstituent selected from the group consisting of hydrogen and loweralkyl groups, and Y" rep-- resents a substituent selected from the classconsisting of hydrogen, lower alkyl groups, and lower hydroxyalkylgroups, with chromium trioxide at a temperature between about 100 C. andabout 250 C.

4. A chromium-containing product obtained by heating an oxazolinecompound having the formula i CH.OH

wherein R, represents the hydrocarbon residue of an acid selected from'the group consisting of higher fatty acids, naphthenic acids, and acidsderived from the liquid phase partial oxidation of petroleum products,with chromium trioxide at a temperature between about 100 C. and about5. A chromium-containing product obtained by heating2-heptadecyl-4-methyl-4-hydroxymethyl-2-oxazoline with chromium trioxideat atemperature between about 100 C. and about 250 C.

6. A chromium-containing product obtained by heating2-peptadecyl-4-methyl-4-hydroxymcthyl-2-oxazoline with chromium trioxideat a temperature between about C. and about 250 C.

7. A chromium-containing product obtained by heating an oxazolinecompound having the formula wherein R represents the hydrocarbon residueof a naphthenic acid, with chromium trioxide at gsiemperature betweenabout 100 C. and about 8. A composition of matter adapted to preventcorrosion of metal surfaces, said composition consisting of from about25 to about 75 per cent by weight of the product defined by claim 1 andfrom about 75 to about 25 per cent by weight of a petroleum distillatesolvent for said Product.

9. A composition of matter adapted to prevent corrosion of metalsurfaces, said composition consisting of approximately equal parts byweight of the product defined by claim 1 and a petroleum distillatesolvent for said product.

10. A composition of matter adapted to prevent corrosion of metalsurfaces, said composition consisting of approximately equal parts byweight of the product defined by claim 5 and a petroleum distillatesolvent for said product.

11. A composition of matter adapted to prevent corrosion of metalsurfaces, said composition consisting of approximately equal parts byweight of the product defined by claim 6 and a petroleum distillatesolvent for said product.

12. A composition of matter adapted to prevent corrosion of metalsurfaces, said composition consisting of approximately equal parts byweight of the product defined by claim 7 and a petroleum distillatesolvent for said product.

13. A composition of matter adapted to prevent corrosion of metalsurfaces, said composition consisting of from about 25 to about '75 percent by weight of a mixture consisting of (1) from about 25 to about '75per cent by weight of a waterinsoluble soap and (2) from about 75 toabout 25 per cent by weight of a chromium-containing product obtained byheating an oxazoline compound having the general formula wherein Rrepresents the hydrocarbon residue of an acid selected from the groupconsisting of higher fatty acids, naphthenic acids, and acids derivedfrom the liquid phase partial oxidation of petroleum products, Y and Yeach represents a substituent selected from the group consisting ofhydrogen and lower alkyl groups, and Y" represents a substituentselected from the class consisting of hydrogen, lower alkyl groups, andlower hydroxyalkyl groups, with chromium trioxide at a temperaturebetween about 100 C. and about 250 C., and from about 75 to about 25 percent by weight of a petroleum distillate solvent for said mixture ofwater-insoluble soap and oxazollne compound. a

14. A process for the preparation of a product adapted to prevent thecorrosion of metal sur- 11 faces, said process comprising heating anoxazoline compound having the general formula RO \OH--Y wherein R.represents the hydrocarbon residue of an acid selected from the groupconsisting of higher fatty acids, naphthenic acids, and acids derivedfrom the liquid phase partial oxidation of petroleum products, Y and Yeach represents a substituent selected from the group consisting ofhydrogen and lower alkyl groups, and Y" represents a substituentselected from the class con sisting of hydrogen, lower alkyl groups, andlower hydroxyalkyl groups, with chromium trioxide at a temperaturebetween about 100 C. to about 200 C.

15. A process for the preparation of a product adapted to prevent thecorrosion of metal 8111" faces, said process comprising heating anoxazoline compound having the general formula hydrogen and lower alkylgroups, and Y" represents a substituent selectedfrom the classconsisting of hydrogen, lower alkyl groups, and lower hydroxyalkylgroups, with chromium trioxlde at a temperature between about C. andabout 250 C..for a time sumcient to efiect the formation of a dark greenviscous liquid reaction product having corrosion preventive properties.

PAUL R. MCCARTHY.

REFERENCES CITIED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,33%,071 Cook et a1 Nov. 9, 19431,364,134 Morgan Jan. 4, 1921

